206 ON GENERATION. 



ambient air contributing somewhat to the effect. Of all this," 

 he says, " you will readily be satisfied if you have a fowl in the 

 house, and dexterously catch the egg in your hand as it is 

 dropping." 



I was myself long fettered by this statement of Aristotle, in- 

 deed until certain experience had assured me of its erroneousness; 

 for I found the egg still contained in the uterus, almost always 

 covered with a hard shell ; and I once saw an egg taken from 

 the body of a living fowl, and still warm, without a shell but 

 covered with a tenacious moisture; this egg, however, did not ac- 

 quire any hardness through the concretion or evaporation of the 

 moisture in question, as Fabricius would have us believe, neither 

 was it in any way changed by the cold of the surrounding air ; 

 but it retained the same degree of softness which it ha,d had in 

 the uterus. 



I have also seen an egg just laid by a fowl, surrounded by a 

 complete shell, and this shell covered externally with a soft and 

 membranous skin, which however did not become hard. I 

 have farther seen another hen's egg covered with a shell every- 

 where except at the extremity of the sharp end, where a certain 

 small and soft projection remained, very likely such as was taken 

 by Aristotle for the remains of an umbilicus. 



Fabricius, therefore, appears to me to have wandered from 

 the truth ; nor was I ever so dexterous as to catch an egg in 

 its exit, and discover it in the state between soft and hard. 

 And this I confidently assert, that the shell is formed internally, 

 or in the uterus, and not otherwise than all the other parts of 

 the egg, viz. by the peculiar plastic power. A statement which 

 I make all the more confidently because I have seen a very 

 small egg covered with a shell, contained within another larger 

 egg, perfect in all respects, and completely surrounded with a 

 shell. An egg of this kind Fabricius calls an ovum centeninum; 

 and our housewives ascribe it to the cock. This egg I showed to 

 his serene Majesty King Charles, my most gracious master, in 

 the presence of many persons. And the same year, in cutting 

 up a large lemon, I found another perfect but very small lemon 

 included within it, having a yellow rind like the other ; and I 

 hear that the same thing has frequently been seen in Italy. 



It is a common mistake with those who pursue philosophical 

 studies in these times, to seek for the cause of diversity of 



